This invention relates to a contact body for an evaporation humidifier or material exchanger for the humidification, cooling and/or cleaning of gases, wherein the contact body consists of a plurality of corrugated material layers which adjoin each other and thus form a space lattice structure, wherein, on the one hand, a liquid can be passed from the top through the contact body and, on the other hand, a gas flow can be passed through in cross flow to the liquid for humidification, cooling and/or cleaning of the gas flow. In addition, the invention relates to an evaporation humidifier or material exchanger with at least one contact body.
Evaporation humidifiers and material exchangers for the initially mentioned purpose, as well as contact bodies for it are known from practical applications. Evaporation humidifiers or material exchangers of the mentioned type are used, inter alia, for humidification of the air and for simultaneous air cooling, for example of residential or office buildings, of warehouses, greenhouses, stables and other rooms or also of technical installations, for removing dust from intake or exhaust air, and for a reactive cleaning of gas or air, e.g. the elimination of odors, such as ammonia, from the waste air of stables. The corrugated material layers arranged side by side and forming the contact body have a large surface in relation to the volume taken up by the contact body, and this surface is wetted by charging the contact body with liquid. By means of the gas flow passing through the contact body in cross flow to the liquid, evaporation of the liquid is achieved and the gas flow is thereby humidified and—as a result of the physically inevitable evaporation cold—cooled at the same time. Solid particles, such as dust particles, from the gas flow are retained in the liquid and thus removed from the gas flow. Moreover, chemical reactions can be caused or, respectively, take place in the contact body between substances in the gas flow and the liquid or substances added to the liquid, such reactions having a desired chemical effect, e.g. cleaning effect.
In the contact bodies known from practice, the corrugation axes in the individual material layers extend rectilinearly from one longitudinal edge to the other longitudinal edge of each material layer which provides the advantage of a simple manufacture of the material layers; however, disadvantageously it results in the air flowing through the contact body having a very low flow resistance and consequently flowing through the contact body at a high flow velocity and an accordingly short dwell period. Moreover, a contact body with such simple corrugated material layers allows light to pass through the material layers in longitudinal direction of the corrugation axes which is a nuisance and undesirable in some applications, especially in stables with an artificial day/night rhythm.
For contact bodies of the aforementioned type and for the described purposes of application, two materials are known from practice for the corrugated material layers. The first material is a paper which, by means of an impregnation, is wettable on the one hand and stiffened on the other hand so that the contact body produced from it is self-supporting. Moreover, the impregnation is to prevent the decomposition of the contact body under the effect of water and air. As a starting material, paper is very economical; however, it has been shown in practice that, despite the impregnation, a contact body of this material has only relatively limited stability and durability. This brings about that a renewal of the contact body is required relatively often. Moreover, this material is not acid-proof so that it is not possible to clean the contact body by means of an acid, e.g. decalcification by means of formic acid or citric acid. Moreover, the low mechanical stability of this material precludes cleaning of the contact body by means of a high-pressure water jet because that would result in the immediate destruction of the paper. In practice, contact bodies of paper accordingly achieve only relatively short service periods, even in case of low burdens.
As a second material for the corrugated material layers, a fiberglass material is known from pertinent practice which is inorganic, corrosion-resistant, hygroscopic and incombustible. This material can, in fact, expect longer durability and stability; however, this is obtained only at the price of high expenditures for the material.
Furthermore, a disadvantage of the known contact bodies is that any normally used bonding of the material layers made of the abovementioned materials with each other is not permanently durable. Especially in contact bodies which are used in interval operation, i.e. which are intermittently moist or wet and intermittently dry, the layer materials in the area of the adhesive connections are especially stressed and lose relatively fast their connection with the adhesive. In the most unfavorable case, this results in a decomposition of the contact body and thus its uselessness. Acids as well are here usually detrimental for bonding the material layers.
DE 28 31 639 C2 presents a plate battery for material and heat exchangers and mist collectors, with a plurality of opposite corrugated plates whose corrugation bottoms form crossing flow channels; with neighboring plates, the corrugation crests touch or are set opposite each other at a gap, and the flow channels have fixtures which influence the flow. Furthermore, it is here provided that transverse walls are arranged in the flow channels, the walls being allocated—touching or at a gap—to the corrugation crests of the respectively neighboring plates, and that so to speak three-dimensional, zigzag flow paths are formed from the flow channel sections of neighboring plates. The plates may consist of plastic and be formed by deep-drawing.
With this known plate battery, it is considered a disadvantage that the corrugations respectively comprise rectilinear corrugation axes extending through the full thickness of the plate battery. So that the air flowing through the plate battery does not flow through it with a dwell period that is too short and at a velocity that is too high, the additional transverse walls must be arranged on the inside of the plate battery which renders its manufacture expensive. Moreover, the continuous rectilinear arrangement of the corrugation axes presents a high risk that liquid supplied from the top into the plate battery passes out at the front and the rear of the plate battery, i.e. at the air upflow side and the air downflow side and is thus discharged from it so that this part of the liquid is practically no longer available for an exchange with the air flow.
DE 26 07 312 B2 presents a device for the humidification of air flowing through a chamber, comprising a plurality of contact bodies for water and air which are mounted in the chamber and which consist of a plurality of parallel, corrugated plates which are watered with water flowing in vertical direction and being separated from each other by means of spacers for the purpose of enabling the flow of air in horizontal direction between the plates. It is here provided that the folds of the contact plates essentially extend vertically, with their fold heights being so low and their fold sequence so short that the water supplied to the plates is retained as a result of the capillary force over virtually the entire plate surface, and that the spacers consist of corrugated support plates whose folds essentially extend horizontally. This device is to solve in particular the problem of preventing the entrainment of water droplets by the air flowing through the device. The material in the contact plates can be either hygroscopic, paper for example, or non-hygroscopic, metal or plastic, for example.
It is considered disadvantageous with this device that the water flows very fast through the device due to the vertically extending flow paths and thus has only a short dwell period in the device. The same applies for the air flow permeating the device and passing through the device on rectilinear horizontal flow paths with low flow resistance and correspondingly high flow velocity. Accordingly, the air flow also has only an unfavorably short dwell period within the device. Thus, the device has a relatively low efficiency with regard to the desired humidification of the air.
From EP 0 554 471 B1, a built-in element is known for heat exchanger, material exchanger or bioreactor systems, wherein the element can be flowed through in counter flow or in cross counter flow along flow paths formed therein of two fluid mediums being in exchange or reaction with each other, wherein the element comprises an inlet side and an outlet side for the first medium and an inlet side and an outlet side for the second medium, wherein the element consists of at least two walls, fastened on top of each other, made of thermoplastic plastic film, with the walls each designed as corrugated surfaces with essentially parallel crest areas and sole areas, with fastening points being arranged in the crest and sole areas and with two neighboring walls fastened onto each other being arranged to each other such that the alignments of the crest and sole areas are at an angle β to each other. It is here furthermore provided that the built-in element comprises—in the direction of flow of one of the two fluid mediums—modularly series-connected element sections, wherein, respectively, from one element section to the next following element section, the flow ratio changes between the two fluid mediums from counter flow at an angle β=0 to cross counter flow at an angle β≠0, or from cross counter flow at an angle β≠0 to cross flow at an angle β=0. This built-in element is used as a so-called trickling element in cooling towers for power stations or chemical plants. They create large surfaces and long flow paths which are to be accommodated in a compact three-dimensional space. The height of the corrugation in the individual layers is usually about 20 to 30 mm; it is thus relatively large. The exterior form can be, for example, that of a cuboid or a cylinder. The fluid mediums which flow through such built-in elements dwell therein, due to the design, for a sufficiently long time for a heat or material exchange in a chemical or biological reaction; the mediums can be, for example, a liquid flowing by gravity through the element and a gas conveyed by a fan through the element. These known built-in elements are used, as a rule, to built counter-flow cooling devices in which water flows from the top to the bottom and air flows from the bottom to the top. The water flowing through the built-in elements is thus cooled by the air flowing in counter flow, with evaporated water escaping with the exhaust air of the cooling tower without any utilization into the atmosphere. Each individual built-in element for a cooling tower is relatively large, with a standard height of 300 mm or more and a width as large. In practice, the length of a cooling tower built-in element amounts to more than 2 meters. Moreover, a plurality of layers, mostly four to six, of the built-in elements are arranged one on top of the other in a cooling tower. In the same manner, a plurality of built-in elements is positioned side by side in each layer. An overall very large built-in installation results within the cooling tower and it must have, by necessity, a considerable size to realize any cooling effect at all for the water. In contrast thereto, the contact body according to this patent application is intended to be used as a spatially small and compact unit which is flowed through in cross flow by a liquid and a gas flow, wherein the liquid flows from top to bottom due to the effect of gravity and the gas flow flows transversely thereto in a mean horizontal direction. Would a cooling tower built-in element—which is per se too large for a contact body—be used as a contact body, the liquid supplied on the top would be discharged to the front and the rear of the contact body already after a relatively short distance so that the liquid would then no longer be available for an exchange with the gas flow. In contrast, it is essential for a contact body according to this patent application that the liquid is kept in the interior of the contact body during its entire flow path from top to bottom through the contact body. For the reasons named above, built-in elements for cooling towers are accordingly not suitable for use as a contact body within the meaning of this application.